Tuesday, September 20, 2011

Let's start with a bit of "history".Duino644 was designed to match with (plug into) the now-discontinued 2416 mono-color LED display from Sure Electronics.Wise Clock 3 board was designed to plug into the 3216 bi-color LED display from Sure.
Both boards have a similar schematic, based on ATmega644, and they share similar features: RTC (DS3231) on I2C, SD card, piezo buzzer, 3 user buttons.

There are a few differences between the 2 boards:

Duino644 has IR receiver, connected on D2, whereas Wise Clock 3 has the Plus button on D2 and no IR receiver;

Wise Clock 3 has D11 connected to pin 2 (CLK) of the 3216 display; on Duino644, since the 2416 display does not require an input on pin 2, D11 is not connected.

Our goal is to adapt the "old" Duino644 board to the 3216 bi-color LED display and run the Wise Clock 3 software on it. This is easily achieved by doing the following hardware hacks:
1. connect the processor's pin 17 to pin 2 of the display's connector (red wire in the photo);
2. solder a bridge between processor's pins 3 and 4 (also visible in the photo);
3. cut out the IR receiver.

Now upload the Wise Clock 3 sketch (download latest version from here).
Plug the Duino644 board into the 5mm display, as shown in the photo above, then power it with the USB miniB cable. Surprisingly, the ensemble looks pretty functional and practical as it is: the buttons are accessible at the top (albeit a bit deep), the board is flush with the display, and the power (USB) socket is on the right side.
The enclosure could be a similar pair of plexiglass plates as used in Wise Clock 3. This bigger Wise Clock 3 would be more suitable to be hang on a wall (rather than sit on a desk).

Note that the Duino644 I tested uses DS3231. A version with DS1307 should work the same (except it will show 0 as the current temperature, I think).

Sunday, September 18, 2011

I recently bought the 5mm LED display from Sure Electronics (same datasheet as the 3mm LED display), just to see how it would work with the Wise Clock 3 board (so I can answer the questions related to this combination).

As expected, just plug the Wise Clock 3 board into the "INPUT" connector of the display (as shown in the photo below), and everything should work. Since you may not want the board to stick out, a better solution would be to connect the two using the ribbon cable provided with the display (you would need to replace the 2x8-pin female header with a a 2x8-pin male header on the Wise Clock 3 board though).

Update (Jul 20, 2014): Photos on how to connect the Wise Clock 4 board to the 5mm display using the ribbon cable can be found here.

This is a huge display. I think it may be visible from 30 meters away (can you imagine Wise Clock 3 in a public plaza?!).

2. If you don't have Wise Clock 3 already, you can order the "Night and day add-on kit" alongside either the board kit or the complete kit. In this case, we will upload the sketch onto the processor for you.

My main requirement for such a shield was to have Arduino-form factor, so that I can just plug it into the Arduino, with no extra work required. Ideally, it would also have an on-board (attached) battery of at least 1000mAh.

Considering that the height of the headers in an Arduino shield is about 8mm and the space between them is about 43mm, the dimensions of the battery should not exceed 50mm x 43mm x 8mm.

None of the three solutions presented here met this requirement, at least not without modifications.

1. 5V DC-DC step-up power pack

This "power pack" shield comes with an on-board (attached) 1500mAh Li-Poly battery. The battery is wider than 43mm, so the headers are not (and cannot be) present. Therefore, the shield is not plug-able, which would technically disqualify it as an Arduino shield.

The "power pack" shield has the Arduino form factor though, with the matching 3 mounting holes, so it can be attached to the underside of an Arduino. (Note: Wiseduino's mounting holes are not aligned with those on Arduino 2009/Uno).
A schematic is not provided.

This battery shield does not come with a battery, but it has 6 big mounting holes that "can help you easily fix the battery pack". I could not find any photo (for inspiration) of the shield with batteries attached.

As shown in the photo above, the battery shield does not have the expansion female headers. It can be plugged into the Arduino, but no other shield plugged on top of it.

3. Solar charger shield V0.9

Seeedstudio discontinued this shield and replaced it with "Solar charger V2.0" (they also have a cheaper, non-shield version, the "Li-Po Rider").

This charger shield uses CN3083 chip. Schematic is published here and documentation can be found here.

The shield does not come with a battery, but it has the expansion headers installed. As expected, the ubiquitous, 68mm x 48mm flat Li-Ion 2000mAh battery (pictured connected to the shield in the photo above) does not fit between the headers, so stacking this shield only works with a smaller (both capacity and dimension-wise) type of battery, probably this 1000mAh one (50mm x 35mm x 5mm).

This battery shield would be the closest to my requirement, only if it had a battery.

Other battery chargers, shields or not, that I did not investigate yet are: